I believe that the old moniker "If you don't value your time why should anyone else" rings true here. Giving it away for free may indeed give you great experience *if* you can allow people to let you into the fold. Consider startups that *can* take on interns but don't simply because its a chore to see a good example of this in motion. If you're not creating value in yourself you're certainly not going to translate that value to your clients, customers etc..